1. Field of the Invention
The present disclosure relates generally to medical devices. More particularly, the present disclosure relates to access needles having distinctly configured stylets that allow for the passage of contrast fluid.
2. Description of the Related Art
The development of minimally invasive methods and devices over recent years has revolutionized the practice of medicine. These methods and devices allow medical professionals to perform a wide variety of procedures while minimizing trauma to the patient. Access needles are used in connection with certain minimally invasive medical procedures. These needles can include a tubular cannula body that can form a conduit between a target site within the body of a patient and a location outside of the patient's body. This conduit can subsequently be used by a medical professional for performing certain procedures in connection with the target site or for running a wire guide therethrough.
An access needle can include a stylet in the lumen of its cannula to avoid inadvertent sample collection at the distal end of the cannula, to provide a sharp tip capable of making a puncture, and to provide some reinforcement to the cannula as it travels to the target site within the body. After the distal end of the needle arrives at its target location within the body, the stylet can be withdrawn, thereby clearing a space through the cannula lumen where, for example, a wire guide may be placed. A medical professional performing such a procedure must be able to determine the exact location of the distal end of the cannula to be sure that it has arrived at the precise target site within the body of the patient.
One method useful for determining the location of the distal end of the cannula within the patient's body is carried out using endoscopic ultrasound (EUS). EUS provides a medical professional with the ability to visualize the location of the distal end of the needle within the patient's body without requiring an open incision, use of large-bore needles, or percutaneous trocars. If this method is used for location purposes, the access needle may comprise an echogenic tip at its distal end. Ideally, EUS can then be used to determine the location of the echogenic tip. However, EUS technology is not always capable of providing the medical professional with precise location data. Thus, it could be advantageous to couple EUS with a different form of location technology either to supplement the EUS data or provide location data in the event that EUS is unsuccessful.
In this regard, fluoroscopy may be used as an additional method to determine the location of the distal end of a needle within a patient's body. In one aspect, fluoroscopy can be used to detect a dye or contrast fluid that has been placed within the patient's body. Specifically, x-rays are emitted through the body of the patient to determine the exact location of the contrast fluid. The resulting image can be transmitted to a monitor and a medical professional carrying out the procedure can then determine if the distal end of the needle is at the target site.
When using this form of location technology, one must be able to supply a radio-opaque dye (e.g. contrast fluid) through the lumen of the cannula and out its distal end. This can be problematic, especially when a stylet is located within the lumen of the cannula. Most prior art stylets are formed of a solid wire and substantially occupy the entire inner diameter of the lumen. As such, they would effectively block or seriously impede the flow of contrast fluid through the cannula lumen. It is thus desirable to provide stylet configurations that will allow for the passage of contrast fluid through the lumen of the cannula without having to provide a larger cannula and/or additional lumen(s).